The Miocene Saint‐Florent Basin in northern Corsica: stratigraphy, sedimentology, and tectonic implications

Abstract

Late early–early middle Miocene (Burdigalian–Langhian) time on the island of Corsica (western Mediterranean) was characterized by a combination of (i) postcollisional structural inversion of the main boundary thrust system between the Alpine orogenic wedge and the foreland, (ii) eustatic sealevel rise and (iii) subsidence related to the development of the Ligurian‐Provençal basin. These processes created the accommodation for a distinctive continental to shallow‐marine sedimentary succession along narrow and elongated basins. Much of these deposits have been eroded and presently only a few scattered outcrop areas remain, most notably at Saint‐Florent and Francardo. The Burdigalian–Langhian sedimentary succession at Saint‐Florent is composed of three distinguishing detrital components: (i) siliciclastic detritus derived from erosion of the nearby Alpine orogenic wedge, (ii) carbonate intrabasinal detritus (bioclasts of shallow‐marine and pelagic organisms), and (iii) siliciclastic detritus derived from Hercynian‐age foreland terraines. The basal deposits (Fium Albino Formation) are fluvial and composed of Alpine‐derived detritus, with subordinate foreland‐derived volcanic detritus. All three detrital components are present in the middle portion of the succession (Torra and Monte Sant'Angelo Formations), which is characterized by thin transitional deposits evolving vertically into fully marine deposits, although the carbonate intrabasinal component is predominant. The Monte Sant'Angelo Formation is characteristically dominated by the deposits of large gravel and sandwaves, possibly the result of current amplification in narrow seaways that developed between the foreland and the tectonically collapsing Alpine orogenic wedge. The laterally equivalent Saint‐Florent conglomerate is composed of clasts derived from the late Permian Cinto volcanic district within the foreland. The uppermost unit (Farinole Formation) is dominated by bioclasts of pelagic organisms. The Saint‐Florent succession was deposited during the last phase of the counterclockwise rotation of the Corsica–Sardinia–Calabria continental block and the resulting development of the Provençal oceanic basin. The succession sits at the paleogeographic boundary between the Alpine orogenic wedge (to the east), its foreland (to the west), and the Ligurian‐Provençal basin (to the northwest). Abrupt compositional changes in the succession resulted from the complex, varying interplay of post‐collisional extensional tectonism, eustacy and competing drainage systems.

Pressure–temperature–deformation–time of the ductile Alpine shearing in Corsica: From orogenic construction to collapse

“…The early Miocene ductile extension and the continuous transition to brittle extensional faulting documented in this study reinforce the significance of the early Miocene rapid exhumation event already detected in the Alpine Corsica region (Cavazza et al, 2001;Fellin et al, 2005;Zarki-Jakni et al, 2004). In this view, conclusive evidence is provided to assert that deposition of the early Miocene (Burdigalian-Langhian) Saint Florent basin (Cavazza et al, 2007;Ferrandini et al, 1998) on top of the exhuming HP units (Fig. 3) occurred during the activity of the ETSZ as an extensional shear zone (Daniel et al, 1996;Gueydan et al, 2003;Jolivet et al, 1998).…”

Seismic markers of the Messinian Salinity Crisis in an intermediate-depth basin: Data for understanding the Neogene evolution of the Corsica Basin (northern Tyrrhenian Sea)

“…Miocene (Zarki-Jakni et al, 2004;Fellin et al, 2005;Cavazza et al, 2007). The oldest pre-MSC formations, which crop out on the Aleria Plain, make up the Burdigalian St-Antoine Fm and Alzelle Fm (Fig.…”

Clastic sedimentation in the Late Oligocene Southalpine Foredeep: from tectonically controlled melting to tectonically driven erosion

“…The most proximal source is identified by the resedimented shallow-water carbonates of the Ternate-Travedona Formation (samples C1C and L2C), or possibly from liberation of clasts directly from the Tertiary shallow shelf which had fed the Ternate-Travedona Formation (Braghieri and Montanari, 1976;Mancin et al, 2001;Cavazza et al, 2007;Brandano and Ronca, 2013). In both cases, the source area has subsequently hidden below the N-eastward movement of the Gonfolite Lombarda Group backthrust, locally named the Mt.…”